JP4074143B2 - Metal bottle cans - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal bottle can in which a screw part is formed in a base part.
[0002]
[Prior art]
In general, a bottle can widely used as a beverage can is formed by drawing a metal plate made of aluminum or an aluminum alloy and then performing an ironing process (Ironing). A base part is formed on the upper part of a so-called can and is manufactured. After the bottle can is filled with the contents, a cap is attached to the base of the bottle can to obtain a bottle can with a cap.
[0003]
Conventionally, a bottle can 1 with a cap as shown in FIG. 3 is sealed with a cap 3 attached to a bottle can 2. A male screw part 5, a bulging part 6, and a curled part 7 are formed on the base part 4 provided in the bottle can 2. The cap 3 is formed with a top surface portion 8, an internal thread portion 9, a pilfer proof portion 10, and a bridge portion 11, and a liner 12 as a seal member is attached to the inner surface of the top surface portion 8. The cap 3 is attached to the bottle can 2 with the male threaded portion 5 of the bottle can 2 and the female threaded portion 9 of the cap 3 fitted and the lower end portion of the pill fur proof portion 10 is wound under the bulging portion 6. The curled portion 7 and the liner 12 are in close contact with each other to be sealed. Moreover, the bottle can 1 with a cap is made into the structure which can endure a prescribed | regulated internal pressure, for example, when the content is a carbonated drink.
[0004]
When opening the bottle can 1 with the cap, when the cap 3 is rotated with respect to the bottle can 2, the female screw portion 9 is guided by the male screw portion 5 to move the cap 3 upward, and the bulging portion 6 and the pilfer The bridge portion 11 is cut by engagement with the proof portion 10, and the curl portion 7 and the liner 12 are separated from each other. Further, the cap 3 is removed from the bottle can 2 by rotating the cap 3. When the cap 3 is rotated at the time of such opening, a knurled portion 13 is formed on the cap 3 in order to prevent the cap 3 from slipping and to improve the holding property. The knurled portion 13 is formed above the female threaded portion 9, and is formed by periodically providing concave portions on a projecting portion having a circular arc cross section provided in the circumferential direction.
[0005]
Further, in the winding process of attaching the cap 3 to the bottle can 2, the cap material on which the female screw portion 9 and the pill fur proof portion 10 are not formed is placed on the bottle can 2, and the cap material is pressed against the bottle can 2. While applying a load, the female screw portion 9 and the pill fur proof portion 10 are formed along the shapes of the male screw portion 5 and the bulging portion 6 of the bottle can 2. As the cap 3 is tightened while applying a load in this manner, the adhesion between the curled portion 7 and the liner 12 is improved, and the cap 3 is sealed well. At this time, the number of effective screw turns of the male screw part 5 and the female screw part 9 is about 1.5 to 1.7.
[0006]
[Problems to be solved by the invention]
By the way, in the bottle can 2 to which the cap 3 as described above is attached, even if a pressure equal to or lower than the prescribed internal pressure is applied to the top surface portion 8 of the cap 3, the female screw portion 9 and the top surface portion of the cap 3 are used. If the distance between the curl portion 7 and the liner 12 is long, the adhesion between the curl portion 7 and the liner 12 is lowered. Further, since the knurled portion 13 is formed between the female screw portion 9 and the top surface portion 8 of the cap 3, there is a problem that it is further easily extended.
[0007]
Moreover, in order to solve such a problem, the space | interval of the internal thread part 9 and the top | upper surface part 8 of the cap 3 is narrowed, that is, the height between the external thread part 5 of the bottle can 2 and the upper end surface of the curl part 7. However, in this case, there was a problem that the cap 3 could not withstand the load pressing the cap 3 and buckled.
[0008]
In addition, since the number of effective screw turns of the male screw portion 5 is about 1.5 to 1.7 turns, there are one portion and two portions where the threads are located from the base end portion to the tip end portion of the base portion 4. As a result, there is a problem that the fitting force between the male screw part 5 and the female screw part 9 is not constant over the circumferential direction of the base part 4. Thereby, even if the internal pressure of the bottle can 2 to which the cap 3 is attached is equal to or less than the specified internal pressure, the cap 3 is displaced upward in one portion of the thread having a weak fitting force, and the curled portion 7 and the liner There was a problem that the adhesiveness with 12 decreased. Further, when the number of effective screw turns is increased to 2.5 or more in order to increase the fitting force, there arises a problem that the torque at the time of opening increases.
[0009]
The present invention has been made under such a background, and can provide a metal bottle can with high buckling strength that can securely seal the base of the metal bottle can with a cap. It is aimed.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention proposes the following means.
The invention according to claim 1 is a metal bottle can in which a curled portion is formed in a cap portion, an inclined portion whose diameter is expanded downward from the curled portion is provided, and a screw portion is formed below the inclined portion. The height from the screw start point of the screw part to the upper end surface of the base part is h (mm), and the slope formed from the screw start point toward the lowest end point of the curled part forms a central axis. The angle is θ (°), the outer diameter that passes through the screw start point is D1 (mm), the outer diameter that passes through the outermost part of the curled portion is D2 (mm), and the curl starts from the upper end surface of the curled portion. When the height to the lowest end of the part is T (mm),
[Expression 2]
And D1 = 33 mm to 38 mm , h is set to 3.6 mm ≦ h ≦ 4.68 mm , and the inclination angle θ is set to a range of 33.2 ° ≦ θ ≦ 54.6 ° . It is characterized by that.
[0011]
According to the metal bottle can according to the present invention, D1 = 33mm~38mm, the height h from the thread start point of the root Ji portion to the upper end face of the base part, 3.6 mm ≦ h ≦ 4.68 mM and a screw The base portion is formed so that the inclination angle θ formed by the inclined portion from the starting point toward the lowest end point of the curled portion with the central axis is in the range of 33.2 ° ≦ θ ≦ 54.6 °. Since the length between the female threaded portion of the cap and the top surface portion is specified, it is difficult to extend between the female threaded portion of the cap and the top surface portion due to the internal pressure of the bottle can attached to the cap. Thereby, the adhesiveness of the curl part of a metal bottle can and the liner of a cap can be maintained favorable. Further, the cap portion is formed so as to be able to withstand the pressing load of the cap in the cap attaching process, and a metal bottle can having a high buckling strength can be formed.
[0014]
The invention according to claim 2 is the metal bottle can as defined in claim 1, wherein the effective thread turns of the threaded portion is set to from 2.0 2.5 Vol.
[0015]
According to the metal bottle can according to the present invention, the effective number of turns of the screw portion is 2.0 or more, and two or more threads are formed from the base end portion to the tip end portion of the base portion. The male screw portion and the female screw portion are securely fitted. The curl portion and the liner are in good contact with each other without the cap being displaced by the internal pressure of the bottle can to which the cap is attached. Thereby, the metal bottle can in which a cap is favorably attached can be formed. Moreover, since the number of effective screw turns of the thread portion is 2.5 or less, an increase in the opening torque can be suppressed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a partial cross-sectional view of a cap portion of a metal bottle can. The cap portion of the metal bottle can (hereinafter referred to as “bottle can”) 2 is provided with a curled portion 7 with its tip bent outward, and the uppermost surface 20 is the curved surface constituting the curled portion 7. It is said that. An inclined portion 21 that expands downward from the curled portion 7 is provided, and a male screw portion 5 having a thread 22 and a thread valley 23 is provided below the inclined portion 21.
[0017]
In addition, a part of the inclined portion 21 gradually protrudes in the circumferential direction at the upper end portion of the male screw portion 5, and the protruding height increases until the height of the predetermined thread 22 is reached, thereby forming a screw start end portion, At the lower end portion of the male screw portion 5, the depth of the screw valley 23 gradually becomes shallower in the circumferential direction, and a screw terminal portion is formed.
[0018]
In the cross-sectional view shown in FIG. 1, the screw start point W1 is the point that becomes the outermost diameter of the screw thread 22, the outer diameter that passes through the screw start point W1 is the screw thread outer diameter D1, and passes through the outermost part of the curled portion 7. The outer diameter to be used is the curl outer diameter D2. The height from the upper end surface 20 of the bottle can 2 to the screw start point W1 is the screw start point height h, and the height from the upper end surface 20 to the lowest end point T1 outside the curled portion 7 is the curled portion height T. .
[0019]
The inclination angle θ of the inclined portion 21 is an angle formed by the inclination from the screw starting point W1 to the upper part of the base portion and the central axis O, and the inclination of the inclined portion from the lowest end point T1 outside the curled portion 7 to the screw starting point W1. An average angle is used.
The inclination angle θ was measured using a Contraser CDH-400 manufactured by Mitutoyo Corporation.
Further, there is a relationship expressed by Equation 1 between the above-described inclination angle θ and the screw start point height h.
[0020]
[Formula 1]
[0021]
From Equation 1, when the thread outer diameter D1, the curl outer diameter D2, and the curl height T are fixed, the screw start point height h is determined when the inclination angle θ is determined, and the screw start point when the inclination angle θ is increased. It can be seen that the height h decreases. From this, it can be seen that the lower limit value of the inclination angle θ is the upper limit value of the screw start point height h, and the lower limit value of the screw start point height h is the upper limit value of the inclination angle θ.
[0022]
Further, the screw start end portion Y, the screw end portion Z, and the effective screw winding portion X will be described with reference to an explanatory view of the male screw portion 5 shown in FIG. The screw start end portion Y and the screw end portion Z are imperfect thread portions in which the height of the thread 22 and the depth of the thread valley 23 are not constant in the circumferential direction. On the other hand, the complete screw portion W is formed with a specified screw height and screw depth. The incomplete screw thread at the screw start end Y is formed so as to protrude gradually from the end point Y1 of the screw start end Y, and the thread start point W1 of the complete screw part W reaches the specified height of the thread 22. It is formed. In addition, the incomplete thread valley in the screw terminal portion Z is formed so that the depth gradually decreases from the screw end point W2 of the complete screw portion W, and the depth disappears at the end point Z2 of the screw terminal portion Z. It is made a face.
[0023]
The effective screw portion X is a screw portion from the effective screw start point X1 in the middle of the screw start end portion Y to the effective screw end point X2 in the middle of the screw end portion Z, including all the complete screw portions W. The effective screw start point X1 is the intersection of the screw start end Y with the bisector L1 of the narrow angle ∠α of the screw start end Y formed by the end point Y1, the center point C, and the screw start point W1. In addition, the effective screw end point X2 is an intersection of the screw end point Z and the bisector L2 of the narrow angle ∠β of the screw end point Z formed by the screw end point W2, the center point C, and the end point Z2.
[0024]
Using the bottle can 2 and the cap 3 as described above, a load bearing test and a leak test were performed. The experiment was carried out by changing the inclination angle θ and the screw start point height h in two types of bottle cans 2 and caps 3 having a thread outer diameter D1 of φ38 and φ33 . In the experiment, a bottle can 2 having a plate thickness of 0.24 to 0.4 mm and an effective screw winding of 8 threads per inch in the male screw portion 5 and several 2.2 turns was used. A cap 3 having a tensile strength of 230 N / mm ² was used.
[0025]
In the load resistance test, the load is increased in the axial direction of the bottle can 2, and the bottle can 2 buckled at less than 1600N is rejected (x), and the bottle can 2 buckled at 1600N or more is evaluated as pass (○). did. In the leak test, the weight of the bottle can 1 with a cap filled with an internal pressure of 0.1 MPa in the normal temperature state is measured, and after passing the bottle can with the cap 1 1 at 37 ° C. for one day, the weight is again measured at the normal temperature state. The bottled can with a cap 1 having a weight difference of 0.2 mg or less was evaluated as pass (◯), and the bottled can with a cap 1 having a weight difference of 0.2 mg or more was evaluated as rejected (×). The experimental results are shown in Table 1.
[0026]
[Table 1]
[0027]
In Table 1, buckling occurs when the screw start point height h is shortened, that is, when the tilt angle θ is increased, and leakage occurs when the screw start point height h is increased, that is, when the tilt angle θ is decreased. I understand. From this, as a comprehensive evaluation, the range of the screw starting point height h and the inclination angle θ where neither buckling nor leakage occurs was evaluated as “good”, and the other was evaluated as “x”. The range in which the overall evaluation is evaluated as ◯ is 3.6 mm ≦ h ≦ 5.6 mm, 33.0 ° ≦ θ ≦ 55.0 °, screw thread in the bottle can with cap 1 having a screw thread outer diameter D1 of φ38. In the bottle can 1 with a cap having an outer diameter D1 of φ33, 3.24 mm ≦ h ≦ 4.68 mm and 33.2 ° ≦ θ ≦ 54.6 °.
[0028]
As described above, the bottled can 1 with a cap according to the present embodiment is formed so that the screw start point height h is in the range of 3.6 mm ≦ h ≦ 4.68 mm. Good adhesion can be obtained. In other words, the internal pressure extends between the internal thread portion 4 and the top surface portion 8 of the cap 3, but the amount of expansion is determined by the screw start point height h, and leakage occurs when the screw start point height h is in the above range. It is possible to make the amount of expansion without doing. Thereby, the bottle can 2 which has favorable sealing performance at a prescribed internal pressure can be formed. Further, even when the knurled portion 13 is formed between the female screw portion 9 and the top surface portion 8 of the cap 3, good adhesion can be obtained by setting the screw start point height h in the above range. .
[0029]
Further, since the inclination angle θ is formed in the range of 33.2 ° ≦ θ ≦ 54.6 ° , it is possible to obtain load resistance capable of withstanding the load pressing the cap 3 in the process of attaching the cap 3. . In addition, since the cap portion 4 is formed so that the effective number of screw turns is 2.0 to 2.5, the cap 3 is securely attached without causing a shift due to the internal pressure of the bottle can 1 with cap. Bottle can 2 can be formed, and an increase in the opening torque can be suppressed.
[0030]
In the present embodiment, the description has been given using the two bottle cans 1 with caps having the thread outer diameter D1 of φ38 and φ33. You may use this invention for.
[0031]
【The invention's effect】
As described above, according to the present invention, by setting the screw start point height h in the range of 3.6 mm ≦ h ≦ 4.68 mm, it is possible to have good sealing performance at the specified internal pressure, and the inclination angle θ By making the range of 33.2 ° ≦ θ ≦ 54.6 ° , it is possible to obtain a metal bottle can that does not buckle in the cap attaching step. Moreover, the metal bottle can which has favorable sealing property can also be obtained by making an effective screw winding number into 2.0 to 2.5 volume.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a cap part of a metal bottle can according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a screw winding portion when a male screw portion is viewed from above.
FIG. 3 is a partial cross-sectional view of a conventional metal bottle can with a cap attached thereto.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bottle can with cap 2 Bottle can 3 Cap 4 Cap part 5 Male thread part 7 Curl part 9 Female thread part 20 Upper end surface 21 Inclined part W1 Screw start point h Height (screw start point height)
θ Inclination angle

Claims (2)

A curl part is formed in the base part, an inclined part that expands downward from the curled part is provided, and a metal bottle can in which a screw part is formed below the inclined part,
The height from the screw start point of the screw part to the upper end surface of the base part is h (mm),
The inclination angle formed with the central axis by the inclined portion from the screw start point toward the lowest end point of the curled portion is θ (°),
The outer diameter passing through the screw starting point is D1 (mm),
The outer diameter passing through the outermost part of the curled part is D2 (mm),
When the height from the upper end surface of the curled part to the lowest end point of the curled part is T (mm),
Satisfied with
D1 = 33 mm to 38 mm , h is 3.6 mm ≦ h ≦ 4.68 mm , and the inclination angle θ is set in a range of 33.2 ° ≦ θ ≦ 54.6 °. Metal bottle can. 2. The metal bottle can according to claim 1 , wherein an effective screw winding number of the screw portion is set to 2.0 to 2.5. 3.